Digital watermarking apparatus and methods

ABSTRACT

The present invention relates to various digital watermarking methods and systems. In one embodiment, a plurality of microlenses can provide a steganographic signal for a handheld device. The pattern corresponds to (or conveys) a unique device identifier. In yet another embodiment, monetary objects are watermarked with payload information to signify currency denomination. The payload information, once extracted, is used to provide feedback regarding the currency denomination. An audio signal or Braille output can be provided as feedback. In still another embodiment, a document management system is based on watermarks. Embedded watermarks are used to track document history, determine document version information, and enhance overall security. Handheld computing devices are advantageously employed with these embodiments.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.09/842,282, filed Apr. 24, 2001 (published as US 2002-0006212 A1). Thesepatent documents are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to digital watermarking, and isparticularly illustrated with reference to handheld computing devicesand data management systems.

BACKGROUND AND SUMMARY OF THE INVENTION

Computers continue to evolve. Time has witnessed huge, lumberingcomputers give way to nimble and powerful desktop, laptop, and handheldcomputing devices. Computational power has increased on almost anexponential curve, while size and portability of computing devices havesignificantly reduced.

People, once shackled to their computers, now experience new-foundfreedom as cell phones, video games, calculators, positioning systems,and personal computing devices become increasingly capable.

Traditional notions of computing are being challenged. Telecommuting isnow common. A person can retreat to the mountains, walk along atrout-filled stream, and still remain connected to the business world. Aparent can cheer on the sidelines of a soccer game and still pack alonga virtual workspace on a handheld device. Advances in wirelesscommunication and satellite systems provide increasing flexibility.

Life-changing advances are anticipated as computers continue to evolve.

The present invention employs digital watermarking techniques to evenfurther increase the applications and flexibility of computers andcomputer-assisted activities. In some embodiments, digital watermarkingtechniques are combined with handheld computing devices. In otherembodiments, digital watermarking techniques are employed with adocument and/or data management systems. In still other embodiments,digital watermarking system and methods provide convenience andcomputing enhancements.

Digital watermarking, a form of steganography, is the science ofencoding physical and electronic objects with plural-bit digital data,in such a manner that the data is essentially hidden from humanperception, yet can be recovered by computer analysis. In physicalobjects, the data may be encoded in the form of surface texturing, orprinting. Such marking can be detected from optical scan data, e.g.,from a scanner, optical reader, input device, digital camera, or webcam. In electronic objects (e.g., digital audio or imagery—includingvideo), the data may be encoded as slight variations in sample values.Or, if the object is represented in a so-called orthogonal domain (alsotermed “non-perceptual,” e.g., MPEG, DCT, wavelet, etc.), the data maybe encoded as slight variations in quantization values or levels. Theassignee's U.S. Pat. No. 6,122,403 and U.S. application Ser. No.09/503,881 (now U.S. Pat. No. 6,614,914) are illustrative of certainwatermarking technologies. Artisans know many others.

Digital watermarking systems typically have two primary components: anencoder that embeds the watermark in a host media signal, and a decoderthat detects and reads the embedded watermark from a signal suspected ofcontaining a watermark (e.g., a suspect signal). The encoder embeds awatermark by altering the host media signal. The decoder componentanalyzes a suspect signal to detect whether a watermark is present. Inapplications where the watermark encodes information, the decoderextracts this information from the detected watermark.

The analysis of the detected data can be accomplished in various ways.Presently, most steganographic decoding relies on general purposemicroprocessors that are programmed by suitable software instructions toperform the necessary analysis. Other arrangements, such as usingdedicated hardware, reprogrammable gate arrays, or other techniques, canof course be used.

Determining orientation of embedded data can be discerned by referenceto visual clues. For example, some objects include subliminal graticuledata, or other calibration data, steganographically encoded with theembedded data to aid in determining orientation. Others objects canemploy overt markings, either placed for that sole purpose (e.g.reference lines or fiducials), or serving another purpose as well (e.g.lines of text), to discern orientation. Edge-detection algorithms canalso be employed to deduce the orientation of the object by reference toits edges.

In one example, subliminal graticule data can be sensed to identify thelocations within the image data where the binary data is encoded. Thenominal luminance of each patch before encoding (e.g., backgroundshading on a document) is slightly increased or decreased to encode abinary “1” or “0.” The change is slight enough to be generallyimperceptible to human observers, yet statistically detectable from theimage data. Preferably, the degree of change is adapted to the characterof the underlying image, with relatively greater changes being made inregions where the human eye is less likely to notice them. Each areathus encoded can convey plural bits of data (e.g., 16-256 bits).

One problem that arises in many watermarking applications is that ofobject or positioning corruption. If the object is reproduced, skewed,or distorted, in some manner such that the content presented forwatermark decoding is not identical to the object as originallywatermarked, then the decoding process may be unable to recognize anddecode the watermark. To deal with such problems, the watermark canconvey a reference signal. The reference signal is of such a characteras to permit its detection even in the presence of relatively severedistortion. Once found, the attributes of the distorted reference signalcan be used to quantify the content's distortion. Watermark decoding canthen proceed—informed by information about the particular distortionpresent.

The assignee's U.S. application Ser. Nos. 09/503,881 and 09/452,023 (nowU.S. Pat. No. 6,408,082) detail certain reference signals, andprocessing methods, that permit such watermark decoding even in thepresence of distortion. In some image watermarking embodiments, thereference signal comprises a constellation of quasi-impulse functions inthe Fourier magnitude domain, each with pseudorandom phase. To detectand quantify the distortion, the watermark decoder converts thewatermarked image to the Fourier magnitude domain and then performs alog polar resampling of the Fourier magnitude image. A generalizedmatched filter correlates the known orientation signal with there-sampled watermarked signal to find the rotation and scale parametersproviding the highest correlation. The watermark decoder performsadditional correlation operations between the phase information of theknown orientation signal and the watermarked signal to determinetranslation parameters, which identify the origin of the watermarkmessage signal. Having determined the rotation, scale and translation ofthe watermark signal, the reader then adjusts the image data tocompensate for this distortion, and extracts the watermark messagesignal as described above.

Such watermarking techniques, and many others known to those skilled inthe art, may be suitably employed with the present invention.

The foregoing and other features and advantages of the present inventionwill be more readily apparent from the following detailed description,which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a handheld computing device.

FIGS. 2A, 2B and 2C are functional diagrams illustrating variouscommunication paths for the handheld computing device of FIG. 1.

FIG. 3 is a flow diagram of a process for inventory management.

FIG. 4 is a flow diagram of a process involving watermarking monetaryobjects.

FIG. 5 is a flow diagram of a process for document management.

FIG. 6A is a functional diagram illustrating a handheld devicecommunicating with a website via the internet.

FIG. 6B is a functional diagram illustrating a watermark decodercapturing a watermark displayed on a handheld computing device screen.

DETAILED DESCRIPTION

The present invention provides increased flexibility through digitalwatermarking technology. The following section describes a computingdevice capable of supporting watermarking software and/or functionality.(It should be appreciated that the illustrated device is only onepossible computing platform. There are many others capable of supportingwatermark embedding and decoding. It is also anticipated that there willbe advances in the handheld computing field, and such advances may besuitably interchangeably incorporated with aspects of the presentinvention.).

Handheld Computing Device

A typical handheld device (also call a Personal Digital Assistant orPDA) can function as a cellular phone, fax sender, and personalorganizer. Some PDAs are hand-held PC with tiny keyboards. Anotherdevice uses a touch-screen and stylus for data entry.

A handheld computing device 10 is now described with reference toFIG. 1. The device 10 preferably includes a processor 12 or otherprocessing circuitry. One common processor is the 206 MHz IntelStrongArm, a 32-bit RISC processor. Of course, many other processors,like those made by Motorola, can alternatively be used. Indeed, as withother components discussed herein, it is anticipated that improvementswill be made with respect to handheld processors. For example, thecomputation power and processing speed of handheld processors willsurely continue to increase. Such improved components may be suitablyinterchanged with the present invention.

Memory 14 is preferably provided in the device. Memory 14 can includeRAM (e.g., SDRAM), ROM, flash memory, optical, and/or magnetic memory.Device 10 can also communicate with external or expansion memory.

Device 10 also preferably includes sufficient bus structure (not shown)to facilitate communication between the various device componentsdiscussed herein. In one embodiment, device 10 includes an expansionslot 13, which is a compartment or communication port to plug expansioncards or devices such as a video card, wireless or satellite modem,additional memory, GPS receiver, sound card, etc., and connect them tothe system bus structure. (Of course, GPS refers to a Global PositioningSystem, which is satellite-based radio positioning system that providesthree-dimensional position, velocity and time information to a GPSreceiver, anywhere on or near the surface of the Earth.).

Device 10 can include a plurality of output devices. For example, device10 can include a display area 16 (e.g., a LCD screen, thin film LCD,etc.), communication port 18, speaker 20, wireless transceiver 22, andprinter 24. (Of course, not all of these components are necessary, andmay be included as optional features or plug-in devices.). Thecommunication port 18 may include a single or a plurality of ports, forexample, an infrared port, serial port (e.g., RS 232 serial port),parallel port, synchronization port, Universal Serial Bus (USB), etc.Communication port 18 may be used to communicate with peripherals (e.g.,web cameras, digital camera, cell phones, modems, a computer network, astand alone computer, scanner, GPS receiver, etc.) or with a hostcomputer. In one embodiment, communication port 18 includes anaudio/video output jack or port.

Wireless transceiver 22 may support a variety of communicationplatforms, and may even include cell phone or satellite transmissioncapabilities. (Alternatively, a cell or satellite phone communicateswith device 10 via communication port 18 or expansion slot 13).

In one embodiment, wireless transceiver 22 communicates with a computernetwork, using a communication protocol such as Bluetooth. As will beappreciated by those skilled in the art, Bluetooth is a wirelesscommunication technology that allows mobile phones, personal digitalassistants (PDAs), PCs and other electronic devices to talk to eachother. Bluetooth is a specification for small form factor, low-cost,short-range radio links between a variety of portable and mobilecomputing devices. For more information, see the Bluetooth SpecialInterest Group web site at www.bluetooth.com. Of course, device 10 maysupport other communication standards, besides Bluetooth.

In one embodiment, wireless transceiver 22 communicates with a hostcomputer 40 to establish an internet or other network connection (FIG.2A). In another embodiment, handheld device 10 communicates directlywith a dial-up or internet service provider, via a mobile phone, modemor wireless connection. In some embodiments, a peripheral device (e.g.,a camera, web cam, scanner, GPS, transceiver, optical sensor, imagingsensor, mouse, keyboard, etc.) communicates with a host computer 40,which then relays the peripheral signal to handheld device 10 (FIG. 2B).In still another embodiment, a peripheral device 42 communicatesdirectly with the handheld device (FIG. 2C).

Printer 24 is an optional component, which may be integral to device 10,or may be in communication with device 10. Printer 24 may include aprint head or thermal printing element. Alternatively, printer 24 mayinclude an ink-jet or laser-jet based printing system.

Device 10 preferably includes input devices, buttons or ports as well.For example, device 10 may optionally include a pen-touch interface toreceive handwritten characters. Device 10 may also optionally include amicrophone 26, through which device 10 responds to voice activatedcommands or to capture audio for recording. (Of course, voicerecognition software may be running to help with the voice-activation.).A fold up (or on a display screen) keyboard can also be used for dataentry. (Of course, communication port 18 is another source for dataentry.). In another embodiment, device 10 includes or communicates withinput devices such as a scanner, mouse, keyboard, modems, wirelesstransceivers, etc., etc.). In another embodiment, device 10 includes atouch screen. (Device 10 may optionally include various launch buttons,which when selected, launch a particular program or software routine.).

Device 10 may optionally include, or communicate with, a digital camera,video capture device, web cam, optical sensor, digital eye module (suchas those provided by LightSurf, Inc., etc.), etc. Such digital eyemodules typically include features such as a complete camera on a chip,CMOS imaging sensor, and/or miniaturized lens and imaging software.Other imaging devices include a CCD image sensor.

Power can be provided to device 10 in many ways. In one embodiment,device 10 includes a battery 28, e.g., such as a lithium-polymerbattery, etc. In another embodiment, device 10 includes an energy cell,which is rechargeable. (Device 10 may also include an interface or portto receive power. USB or cradle recharging is even possible.). An on/offswitch can also be provided for device 10. (In one embodiment, softwareautomatically shuts down the device 10 after a predetermined period ofinactivity. Power is conserved as a result.).

Various software applications can be stored and run on device 10.Microsoft Corp. even has a Pocket PC Windows operating system. Palm andHandspring have their own operating systems. Many other software modulesand applications are supported on handheld devices, such as wordprocessing, device drivers, internet surfing or exploring, databasemanagement, communications, personal organization software, and many,many others.

As will be appreciated by one of ordinary skill in the art, suitablesoftware programming instructions executing via processor 12 can be usedto affect various types of watermark embedding and detection. Toincrease performance, software-programming instructions can beoptionally written as fixed-point based code, instead of floating-pointbased code. In another embodiment, only watermark embedding or detectingsoftware-programming instructions are stored on device 10, and executedwhen needed.

There are many other handheld devices offered by a gaggle ofmanufactures, which may suitably support watermarking software orwatermarking functionality a few such manufacturer and products are: HP(e.g., the Jornada 520/540 series), Compaq (e.g., the iPac Pocket PC),Handspring, Inc., and Palm, Inc. Some of these handheld devices combinecomputing, telephone/fax and networking features. Of course, it isexpected that these devices, and others, will continue to improve. Suchimprovement may be readily incorporated with the present invention.

User Applications

The following sections disclose various inventive methods and systems,in which device 10 executing watermarking software (decoding and/orembedding) is employed. In some cases, a networked computer, instead ofa handheld device is used. (Although some of the following applicationsare described with reference to a handheld computing device, it will beunderstood that a compliant desktop or laptop computer couldalternatively be employed. The term “compliant” in this disclosureimplies that the device is able to embed and/or decode digitalwatermarks.).

Inventory Control

A compliant handheld device 10 is ideal for helping to track and manageinventory. Consider a warehouse or store with inventory (e.g., 100widgets and 50 wobits.). The handheld device 10, via printer 24, printsa watermark onto each of the inventory items (see FIG. 3, step S1).Preferably, the watermark is directly printed or impressed onto aninventory item. Alternatively, a watermark is printed on a sticker oradhesive tag that is applied to the inventory item. An inventorywatermark preferably includes a unique identifier, which identifies thetype of inventory item (e.g., a widget or wobit), and optionally, anitem number identifier (e.g., widget number 26). In another identifyingscheme, each inventory item is uniquely identified. Unique identifiers,representing inventory items, can be maintained in an inventory list(step S2). Of course, database management software can be used to helpmanage and update the inventory list.

The printing of the watermark can encompass artwork or printing on theinventory item or tag, the printed background, numbering, lines on theitem or tag, a laminate layer applied to the item or tag, surfacetexture, etc. If a photograph, line design, or drawing is present, ittoo can be encoded. A variety of watermark encoding techniques aredetailed in the patent documents discussed herein; artisans in the fieldknow many more.

Device 10 can maintain an inventory listing for each printed tag. Ofcourse, device 10 can maintain a subset of inventory information aswell. Alternatively, device 10 can communicate with a central computer40, which maintains the inventory listing. Checkout stations, rovingcashiers, and inventory controllers can carry or be equipped withcompliant computing devices. These devices track inventory (e.g., byreading the embedded watermark, extracting the identifier(s), andrecording or communicating activity) as it is shelved, shipped, returnedand/or sold (step S3). For example, a cashier with a compliant devicereads a watermark as an inventory item is purchased. The uniqueidentifier and, optionally, a unit number, is extracted from thewatermark. The inventory listing can be updated accordingly to reflectthe purchase (or shipment, or shelving). In one embodiment, a pluralityof handheld devices is in communication with a host computer. Changes ininventory can be updated in real-time. In another embodiment, compliantdevices periodically communicate with the central computer. In stillanother embodiment, a handheld computing device maintains the centraldatabase. Inventory can be tracked efficiently as such.

Verification Aids for the Seeing Impaired

Another method and system that is particularly well suited for practicewith a compliant handheld device involves watermarking monetary objects(e.g., currency, bills, coins, treasury bonds, cashier's checks,traveler's checks, notes, food stamps, etc.). Monetary objects arewatermarked to indicate denomination, such as the amount of the object.In one embodiment, a watermark payload indicates that a five-dollarbill, is in fact, a five-dollar bill. Alternatively, in anotherembodiment, the watermark itself identifies the respective type ofmonetary object. Optionally, a monetary object is digitally watermarkedto include the source of the object, e.g., U.S., Euro, France, Mexico,etc.

A monetary object is present to a compliant reading device, such as ahandheld device 10 (see FIG. 4, step S10). The compliant device reads adigitally watermarked monetary object, and extracts the denominationinformation (step S11). The denomination information is handled by thecompliant reading device (or a device in communication with thecompliant device), which provides feedback to a user (step S12).

In one embodiment, the compliant reading device includes audio or voicesynthesis, which announces the monetary denomination (e.g., announces“ten dollars,” when a ten dollar bill is decoded). In anotherembodiment, the compliant reading device communicates with a Brailleoutput device, which signals the monetary object's size. (Othertextile-based feedback can alternatively be provided.). A seeingimpaired individual is no longer dependent upon a potentiallyunscrupulous cashier when making payments or receiving change. Instead,the individual digitally reads the embedded watermark to determinecurrency size and/or type and receives an audible (or other) indicationof bill or currency size.

To implement such, watermark payload bits are set to identifycorresponding currency. When decoded by a compliant device, the payloadbits are used by a device to index a predetermined wave (or audio) file.The file can be rendered or played to announce the corresponding bill(or other monetary object) size. The payload bits can be feed directlyto an audio-synthesis chip. The audio-synthesis chip can bealternatively preprogrammed to respond to various payloads. For example,the payload bits of a five dollar bill trigger an audio synthesis of“five” or “five dollars,” etc. Alternatively, the payload bits can behandled by software, which activates a feedback device to providepredetermined feedback based on the payload bits. The feedback can bechanged from time to time, but is still triggered based on the payload.In another embodiment, the type of watermark, and not the payload,triggers like functionality.

(Although this embodiment is particularly well suited for handhelddevices, the present invention is not so limited. Indeed, a cashierstation or checkout stand could be equipped with a compliant readingdevice, which is available to seeing impaired individuals. The compliantdevice can be periodically inspected to ensure that it is providingaccurate results. The complaint device could decode the watermark andrespond accordingly, e.g., announce bill size based on the type ofwatermark, or on a watermark's payload. A compliant device could also beinternet-based, for example, using Digimarc MediaBridge technology. Themonetary object identifier is decoded and provided to a Digimarc server(e.g., an online server). The watermark identifier is associated with aURL or other information. The URL or other information includes thecorresponding correct feedback to be provided to the user. In this case,an audio signal or file can be provided to announce the denomination. Instill another embodiment, a signal from the corresponding URL serveractivates a Braille or other output device.).

Street signs, restaurant menus, grocery store isles (and goods) can bewatermarked to provide similar feedback. In this case, a sign, menu oritem can be embedded with a unique identifier. A compliant device canextract an identifier, which it relays (e.g., via a wireless or othercommunications channel) to a central database. The central databaseretrieves related information (audio files, Braille enabling commands,etc.) and communicates such to the querying device. In one embodiment,the database is accessed via the internet. In another embodiment, ahandheld device includes a library or database of identifies and relatedinformation. In this case, the handheld device need not query an onlinedatabase, but may look to its stored database.

Document Management System

Digital watermarks may also be used to help manage documents and providequality assurance. As will be appreciated, there are severaldocument-management and quality assurance standards in place. ISO 9000is one example. There are many others. Some such standards mandate thatonly the most recent version of a printed document be retained, adocument history be maintained, and/or security be implemented.

Consider the following embodiment. Each time a document is printed, anidentifier is steganographically embedded therein in the form of adigital watermark. The identifier identifies document data, e.g., suchas a document file name, document version number, creation and/or printtime, author, edited by, printer location, etc. (Once obtained, thisdocument data can either be contained in the embedded watermark itself,or contained in a database to which the watermark represents a pointer,or both.). A database can be used to track documents and revisions tosuch, based on unique identifiers assigned per print, or edit, orsession, or etc.

A printed, watermarked document then becomes a portal to relatedinformation, or a gatekeeper to help track document history. Consider atypically office situation, in which documents are printed and thenedited/updated, and where several people have access to an electroniccopy of the document. A user presents a printed document to a compliantdevice. An image of the document is captured by an input device, e.g.,via digital camera, optical sensor, laser scanner, web cam, digital eye,CCD or CMOS imaging sensor, or scanner. The embedded watermark isdecoded from the captured image. Related information can then bedetermined from the database. For example, the extracted watermarkinformation uniquely identifies the document, e.g., via the documentdata. If the document is in an electronic form, it to can be digitallywatermarked. The watermark can be used to track and identify thedocument.

In one embodiment, the document data is compared with the databaseinformation to determine whether the printed copy is the most recentcopy. Additional information can be determined as well. For example, theauthor of the latest revisions can be identified, upcoming deadlines, orsensitive conditions (e.g., contract terms or confidentialityagreements) can be presented to the user. (Preferably the compliantcomputing device includes a user interface, through which suchinformation is relayed. In another embodiment, such information iscommunicated to a user's designated handheld device.).

Now consider an embodiment implemented in a business or home-officeenvironment. Say a business team is meeting in conference room B, on thefirst floor of a building. In the meeting, it becomes apparent that noteveryone in the group has the same documentation. Luckily, the neededdocuments are watermarked with document identifiers. The watermarkeddocuments are presented to a compliant device, which extracts anddecodes the respective document identifier (see FIG. 5, step S20). Auser interface allows the meeting participants to select a printingoption and printing location. (In the case of a handheld device, thedevice communicates, perhaps wirelessly, with a network communicationport. The user interface may reside on the handheld device itself.). Theidentifiers are associated in a network-accessible database according tocorresponding electronic documents. An extracted, watermark identifieris used to interrogate the database to find an associated, orcorresponding, electronic document (e.g., a Word file, Excelspreadsheet, PDF file, etc.). Network routing software determines aprinter nearest (or convenient) to the compliant device and renders theelectronic document to the printer for printing. Optionally, a messageis communicated to the compliant device, indicating the printinglocation.

So-called fragile watermarks can be embedded within a document. Afragile watermark can be designed to be lost, or to degrade predictably,when the data set into which it is embedded is processed in some manner.Thus, for example, a fragile watermark may be designed so that if animage is JPEG compressed and then decompressed, the watermark is lost.Or if the image is printed, and subsequently scanned back into digitalform, the watermark is corrupted in a foreseeable way. (Fragilewatermark technology is disclosed, e.g., in commonly assignedapplications Ser. Nos. 09/234,780, 09/433,104, 09/498,223, 60/198,138,09/562,516, 09/567,405, 09/625,577, 09/645,779, and 60/232,163.). Bysuch arrangements it is possible to infer how a data set has beenprocessed by the attributes of a fragile watermark embedded in theoriginal data set.

In one embodiment, a second watermark is embedded along with a fragilewatermark in a document. The second watermark can include informationpertaining author, printer, document version, user, etc. In thisembodiment, when a compliant device decodes a document, and the fragilewatermark is not detected, the document is determined to be a copy orduplicate. Information from the second watermark can be used to identifythe source of the document. (The printer or user can be identified todetermine a potential security breach.).

Event Tickets

Movie and other event tickets may be purchased on-line from varioussources. A ticket may comprise many forms, including an authorizationcode, digital image, audio signal, text file, and digital signal. Theticket preferably includes a unique identifier or purchase code embeddedtherein. In one embodiment, the ticket is transferred to a purchaser'shandheld device. Alternatively, the online movie ticket retailertransmits a ticket in the form of a payload, authentication code, ordigital file to the user's computer. A plug-in on the user's computer islaunched, which incorporates the ticket information when creating awatermarked image. (A handheld device can directly communicate with anonline website, as shown in FIG. 6A, to retrieve a ticket. Or thehandheld device can communicate with the website via a host computer, asshown in FIG. 2A.).

As noted in Assignee's U.S. Patent Application 60/257,822, filed Dec.21, 2000, a watermarked image can be presented on the LCD display, andcaptured by a web cam for various purposes. Accordingly, in a preferredembodiment, a watermarked ticket image is displayed on a handhelddevice.

At the movie theater, the ticket purchaser presents the handheld device,showing the watermarked image on the display screen, to a compliantwatermark decoder 50, as shown in FIG. 6B. The decoder verifiesauthentic tickets by opening a gate or enabling a visual confirmation,e.g., a green light, or via a graphical user interface and/or with humanintervention. The movie theater decoder can download a list of authenticpayloads or identifiers prior to each movie showing or session, mayquery an online database to verify each ticket. The extracted identifiercan be compared to the authentic identifiers to confirm a valid ticket.When the ticket identifier matches one of the authorized identifiers,the ticket is verified, and entry is permitted.

(Fragile watermarks are alternatively embedded in the electronic ticketto help avoid counterfeiting.)

Credit at a concession stand (or coupons for such) can be obtained bytechniques like those above.

In still another embodiment, a movie or event poster (or flyer,advertisement, etc.) is digitally watermarked to include related eventinformation, or a pointer to such information. A compliant handhelddevice extracts the embedded watermark information. In a firstembodiment, an extracted watermark pointer (or index) is used tointerrogate a database point to a web address (e.g., via a URL). Thedatabase (or web site) may include data records, including related eventinformation. For example, for a movie poster, the related informationmay include ticket purchase information, trailers or clips, moviereviews, behind the scenes information, and much, much more. Thedatabase can be accessed via the internet, or via a network system.Alternatively, a database can be downloaded onto the handheld device.

Unique Device Identifiers

A handheld device can be configured to have a unique device identifier,presented via its display. Typically, a handheld device displaycomprises a plurality of pixels. In one embodiment, a microlens is addedfor each pixel, or a subset of the plurality of pixels. (Some so-called“camera-on-a-chip” devices are currently equipped with microlenses.These camera-on-a-chip devices use an all-CMOS process to build both asensor array and additional on-chip signal-processing logic. In oneexample, the sensor array is organized as a 1,280×1,024 array, whichcorresponds to the higher resolution SXGA standard. A microlens for eachpixel is added to enhance sensitivity, and provided for special colorfilter arrays.).

For handheld devices, the microlenses can be used to vary luminance ofpixel elements. Indeed, the microlens can polarize light, e.g., in ahorizontal and/or vertical direction. Microlenses can be arranged tocreate a pattern of horizontal and/or vertical polarizations. A uniquedevice identifier can be determined from the pattern. (In a firstembodiment, a pattern can be constructed to steganographically hidedata, e.g., a device identifier. In another embodiment, the patternmathematically corresponds with a device identifier. In still anotherembodiment, the pattern reveals a series of binary signals, which areused to determine the device identifier. In yet another embodiment, aFourier analysis of the pattern reveals information used to determinethe identifier. Artisans in the field know other ways to correlate apattern with an identifier. Such may be suitably employed with thepresent invention.).

To an unfiltered eye (or camera), the polarized display appears normal.The various horizontal and/or vertical polarizations are typicallyundetected.

Adding a polarized filter, however, reveals the polarized luminancepattern. In this embodiment, an input device, e.g., a camera, web cam,optical sensor, imaging sensor, etc., includes a filter (e.g., apolarized filter, a luminance filter, etc.), which exposes the polarizedpattern. An input device captures an image of the handheld devicedisplay (e.g., as shown in FIG. 6B). The captured image includes apolarized pattern, which includes (or hides) a unique device identifier.In the preferred embodiment, software is used to analyze a pattern anddiscern the corresponding device identifier.

In another embodiment, the device identifier is dynamic, in that it canchange. To accomplish such, a set of microlens includes a bus structure(or energy receptacles) to receive electricity or energy (hereafter bothreferred to as “energy”). Energy is applied to the set of microlens tochange their respective polarizations. The polarization pattern isthereby changed. Accordingly, the unique identifier can be changed.Software, running on the handheld device can be used to provide aninterface to help change the unique identifier.

There are many applications involving such a device identifier. Forexample, referring to the “Event Tickets” section above, a user couldpresent her handheld device when purchasing tickets. A filtered image ofthe handheld device display is captured to determine the unique deviceidentifier. The watermarked ticket image (or authorization code)includes the corresponding device identifier. At the event location(e.g., movie theater), the watermarked ticket image is displayed via thepolarized display. An image of the display is captured. The capturedimage (e.g., of the watermarked ticket image) is decoded to extract boththe ticket authorization identifier and the polarized device identifier.An image of the display can be captured via a polarized-filter inputdevice, which can be used to determine the unique device identifier. (Ofcourse, one input device can also be used with different filters or afilter that allows both polarization filtering and typical imagecapture.). The decoded device identifier is compared with the captureddevice identifier. If they match, then entry is allowed (assuming theauthorization matches.). In one embodiment, the embedded ticketauthorization is the corresponding device identifier.

As a copy control, multi-media content can be bound to a particularhandheld device via the device's display identifier.

A device identifier can be used in a security system or network access.For example, verifying the device display identifier is one step in asecurity system. (Such a system may also include entry of a PIN orpassword, etc.).

Of course there are many other applications with respect to uniquelyidentifying a handheld device via a polarized display.

Handheld Devices as Scanners

A handheld device equipped with, or in communication with, a digitalcamera or web camera, can be used as an image scanner. A digital or webcamera captures image patches or swatches. Assuming a watermarkeddocument is imaged, the captured pieces can be stitched back together toform the original image.

The watermark is embedded to include using an orientation or gridsignal. The grid signal is redundantly embedded within a document. Thegrid signal can be key on, and used as a template when stitching piecestogether. Specifically, image pieces or swatches can be orientedaccording to the grid signal, and then matched with adjacent pieces.

Accordingly, a handheld device (and an input device, e.g., a web cam)becomes a scanner.

Conclusion

The foregoing are just exemplary implementations using digitalwatermarking technology. It will be recognized that there are a greatnumber of variations on these basic themes. The foregoing illustratesbut a few applications of the detailed technology. There are manyothers.

While this application discusses a handheld computing device, thepresent invention is not so limited. Of course, a compliant device mayinclude a desktop or laptop computer, or even a compliant kiosk.

To provide a comprehensive disclosure without unduly lengthening thisspecification, the above-mentioned patents and patent applications arehereby incorporated by reference. The particular combinations ofelements and features in the above-detailed embodiments are exemplaryonly; the interchanging and substitution of these teachings with otherteachings in this application and the incorporated-by-referencepatents/applications are also contemplated.

The above-described methods and functionality can be facilitated withcomputer executable software stored on computer readable mediums, suchas electronic memory circuits, RAM, ROM, magnetic media, optical media,removable media, etc. Such software may be stored on a handheld readingdevice. Instead of software, the watermarking functionality may behardwired.

The section headings in this application (e.g., “Handheld ComputingDevice”) are provided merely for the reader's convenience, and provideno substantive limitations. Of course, the disclosure under one sectionheading may be readily combined with the disclosure under anotherheading.

In view of the wide variety of embodiments to which the principles andfeatures discussed above can be applied, it should be apparent that thedetailed embodiments are illustrative only and should not be taken aslimiting the scope of the invention. Rather, we claim as our inventionall such modifications as may come within the scope and spirit of thefollowing claims and equivalents thereof.

1. A method of determining a size or denomination of a momentary objectcomprising: decoding a watermark embedded in a monetary object, thewatermark including data corresponding to a denomination of the monetaryobject; and based on the data, determining feedback to indicate thedenomination of the monetary object; and providing the feedback.
 2. Themethod according to claim 1, wherein the provided feedback comprises anaudible announcement or a series of audible sounds of the denominationof the monetary object.
 3. The method according to claim 1, wherein theprovided feedback comprises Braille typography indicating thedenomination of the monetary object.
 4. The method according to claim 1,wherein said decoding comprises analyzing optical scan datacorresponding to the monetary object.
 5. The method according to claim1, wherein the provided feedback comprises Braille feedback.
 6. Themethod according to claim 1, wherein a handheld computing device,decodes the watermark.
 7. A method of managing documents comprising:encoding a document with a digital watermark including a documenthistory identifier; storing the document history identifier in adatabase, and associating related document history with the documenthistory identifier; and upon receipt of a decoded digital watermarkidentifier, indexing the database with the identifier to access therelated document history.
 8. The method according to claim 7, whereinthe related document history comprises document version information. 9.The method according to claim 8, wherein the document versioninformation includes both version information pertaining to thedocument, and information pertaining to a later version.
 10. The methodaccording to claim 7, wherein the related document history comprises oneof document version data, creation time, author and last editedinformation.
 11. The method according to claim 7, wherein the identifiercomprises at least document version information.
 12. A handheldcomputing device comprising: a display including a plurality of pixelelements; and a set of microlenses, wherein each of the set ofmicrolenses corresponds with a pixel element, wherein the microlensesare arranged to create a pattern, the pattern providing to a uniqueidentifier for the device.
 13. The handheld computing device of claim 12wherein the lenses are polarized.
 14. The handheld computing device ofclaim 12 further comprising electronic circuitry communicating with theset of microlenses, wherein the electronic circuitry operates to changethe unique identifier.
 15. The handheld computing device of claim 12wherein the unique identifier comprises a steganographic identifier. 16.The handheld computing device of claim 12 wherein the device comprises acell phone.
 17. A handheld device comprising: an image sensor arraycomprising a plurality of pixel elements; and a plurality of lenses,wherein the plurality of lenses are arranged to provide a steganographicsignal.
 18. The handheld device of claim 17 further comprisingelectronic circuitry to energize at least some of the lenses, whereinenergizing at least some of the lenses changes the steganographicsignal.
 19. The handheld device of claim 17 wherein the device comprisesa cell phone.
 20. The handheld device of claim 17 wherein for each pixelelement there is provided a lens.